Hydraulic piston pumps



Dec. 12, 1967 A. RATEAU HYDRAULIC PISTON PUMPS 3 Sheets-Sheet 1 Filed Oct. 22, 1965 y l 4 w 1%? Dec. 12, 1967 A. RATEAU 3,357,358

HYDRAULIC PISTON PUMPS Filed Oct. 22, 1965 a Sheets-sheet 2 United States Patent 3,357,358 HYDRAULIC PISTON PUMPS Alexis Rateau, Ave. Elisee Reclus, Paris, France Filed Oct. 22, 1965, Ser. No. 501,575 Claims priority, application France, Jan. 18, 1965, 2,321, Patent 1,431,741 4 Claims. (Cl. 1035) This invention relates to hydraulic piston pumps of the type adapted under constant rotational velocity conditiOns to deliver a variable output as a function of the reaction torque.

When a hydraulic pump is to be rotatably driven from an electromotor or a combustion engine it is advantageous to cause the pump to revolve at a constant speed corresponding to its best output efficiency, but it is still more essential to keep the driving motor or engine revolving at a constant speed corresponding to its maximum efficiency.

In order to maintain at constant values the velocities of rotation of the pump and of its driving motor while delivering a constant output, it is necessary to cause the pump output to vary as a function of the reaction torque applied for example to the output shaft of a hydraulic motor rotatably driven by the fluid delivered by the pump.

It is the essential object of the present invention to provide a hydraulic piston pump delivering under constant rotational speed conditions an output variable as a function of the reaction torque.

To this end, the hydraulic piston pump according to the present invention, which comprises a number of cylinders disposed radially at spaced angular intervals about a rotary shaft provided with an eccentric member controlling the reciprocating movements of the pistons slidably mounted in said radial cylinders, is characterized in that it comprises means such that the throw of said eccentric member decreases gradually and automatically as the pressure exerted by said pistons on the fluid contained in said cylinders increases, said throw possibly becoming zero when said pressure attains a predetermined maximum value.

According to a specific form of embodiment of this invention, the thrust is transmitted from said eccentric member to the piston push members by means of an intermediate ring member surrounding with a certain play said eccentric member, said ring member comprising on each one of its two lateral or end faces frustoconical inclined cam surfaces adapted to co-act with frustoconical cam surfaces of opposite inclination formed respectively on the registering inner faces of two annular members surrounding said eccentric member and concentric thereto, dis posed on either side of said ring member, and resilient means constantly urging said annular members towards each other in order to return said ring member to its maximum throw position, said ring member being adapted, by pushing said annular members outwards through the medium of the pressure exerted on the co-a-cting inclined cam surfaces, to resume more or less reduced eccentric positions, down to zero throw.

The resilient means constantly urging said two annular members for adjusting the throw of said intermediate ring member may consist of dished spring washers interposed between said annular members and external abutment members.

To avoid or reduce frictional contacts and therefore improving the efiiciency and reduce wear, a thrust ring may be mounted on the intermediate ring member, between this ring member and the piston push members, needle bearings being interposed between these two ring members.

According to another feature characterizing this invention the eccentric member revolves with the minimum clearance in a cylindrical chamber fed from the reservoir or fluid return line of the hydraulic motor driven from the pump and supplying the pump cylinders through delivery pipe lines or ducts disposed tangentially, said chamber thus constituting in conjunction with said eccentric member a rotary pump of which the efficiency adds itself to that of the piston pump.

The attached drawing illustrates diagrammatically by way of example a typical form of embodiment of the present invention. In the drawing:

FIGURE 1 is a longitudinal axial section showing the assembly with the ring members in their initial maximumthrow position;

FIGURE 2 is a view similar to FIGURE 1 but showing the ring members in their zero-throw position;

FIGURE 3 is a cross-sectional view taken upon the line III-4H of FIGURE 1.

The pump illustrated in the drawing comprises a cylindrical pump body 1 formed with integral radial cylinders 2, 3 and 4, and a pair of flanges 5, 6 through which extends the drive shaft 7 carried by needle bearings 8 and 9; between these two bearings the shaft 7 comprises an eccentric port-ion divided into two end bearing portions 10 and 11 of relatively large diameter and a central portion 12 of smaller diameter, the difference in diameter between these lateral and central portions corresponding to twice the throw e.

The intermediate ring member 13 is mounted concen trically to these eccentric portions 10 to 12 but have no direct contact with the central portion 12 of the eccentric; the ring member 13 is formed with frustoconical lateral inclined cam surfaces 14 and 15 engaging corresponding cam frustoconical surfaces 16 and 17 of opposite inclination formed on the two inner registering surfaces of a pair of lateral annular members 18 and 19 respectively, mounted on said eccentric lateral portions 10 and 11; besides, spring dished washers 2t and 21 bear with their outer faces respectively on a shoulder 22 or shaft 7 and on a ring 23, and with their inner faces against said lateral annular members 18 and 19; these spring washers exert their resilient pressure in the direction of the arrows f and of FIGURE 1 to keep the intermediate ring member 13 in the maximum throw or eccentric position shown at e in this figure.

A thrust ring 24 carried by said intermediate ring member 13 through the intermediary of needle bearings 25 and 26 transmits the reciprocating thrusts resulting from the rotation of the eccentric portions 111 to 12 to the push members 27 of said three radial cylinders 2 to 4, and also to pads 28 of adequate elastomer, the elastic deformat-ion of these pads modifying the volumetric capacity of the inner chambers 29 of cylinders 2 to 4, thus determining the pump operation.

When the fluid pressure f increases in the cylinders 2 to 4, the inclined cam surfaces 14 and 15 of the intermediate ring member 13 exerts a certain thrust against the oppositely inclined cam surfaces 16 and 17 of annular members 18 and 19, thus causing lateral thrusts f and f to be exerted on said annular members; when these thrust valves exceed those, f and f2, of the dished spring washers, they cause an outward sliding movement of annular members 18 and 19 and therefore a reduction in the throw e which may even become zero as shown in FIGURE 2; the drive shaft 7 and intermediate ring member 13 will thus revolve without producing any pump output.

The fluid compressed in chamber 29 by the intermediate ring member 13 when this ring member 13 is not in its zero-throw position, thrust ring 24 and push member 27, unseats the ball valve 30 and the fluid can thus escape through the duct 31 to the pressure-fluid pipe line (not shown); after use, this fiuid is returned by means of a return line (not shown), for example an axial duct formed in the shaft 7 and connected to a radial extension thereof leading into the cylindrical chamber 32 in which said intermediate ring member 13 is rotatably mounted, so as to shift the thrust ring 24, this assembly constituting an auxiliary rotary pump forcing the fluid through the tangential duct 33 (FIGURE 3) and another ball valve 34 back into the chamber 29 of cylinder 2.

Of course, the specific form of embodiment described hereinabove with reference to the attached drawing should not be construed as limiting the scope of the invention since many modifications may be brought thereto as will readily occur to anybody skilled in the art, without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim is:

1. A hydraulic piston pump comprising a rotary shaft having an eccentric portion, a plurality of radial cylinders disposed at spaced angular intervals about said eccentric portion of said rotary shaft, an intermediate ring member surrounding with a certain clearance said eccentric portion and controlling the reciprocatin-g movements of the pistons slidably mounted in said radial cylinders, said ring member having formed on each one of its two end faces frustoconical cam surfaces adapted to co-act with frustoconical cam surfaces of opposite inclination formed respectively on the registering inner faces of two annular members surrounding said eccentric and concentric thereto, said annular members being disposed on either side of said ring member, and resilient means constantly urging said annular members towards each other to return said ring member to its maximum eccentric position, said ring member being adapted, by pushing said annular members outwards through the medium of the pressure exerted on the co-acting inclined cam surfaces, to resume more or less reduced eccentric positions, down to zero throw.

2. A pump as set forth in claim 1, wherein said resilient means constantly urging said two annular members adjusting the degree of throw of said intermediate ring member towards each other consist of dished spring washers.

3. A pump as set forth in claim 1, wherein a thrust ring is mounted on said ring member, between said ring member and said pistons, and needle bearings are interposed between said ring member and said thrust ring.

4. A pump as set forth in claim 1, adapted to drive a hydraulic motor and comprising a cylindrical chamber in which said eccentric portion of said shaft is rotatably mounted with the minimum clearance, said chamber being fed with the return fluid from the hydraulic motor driven by the pump, and feeding in turn the pump cylinders through the medium of tangentially disposed fluid delivery ducts.

References Cited UNITED STATES PATENTS 1,122,124 12/ 1914 Johnsen 103-174 2,263,786 ll/1941 Rumpp 103-38 2,327,787 8/1943 Heintz 103-37 2,393,175 1/1946 Laskey 103-37 2,871,846 2/1959 Zimmerman 103-174 2,913,991 11/1959 'Dolza et al. 103-148 2,974,599 3/ 1961 Dolza 103-148 3,043,228 7/1962 Bennett 103-38 3,073,178 '1/1963 Barnes et al. 103-174 3,270,684 9/1966 Pasquali et al. 103-143.

LAURENCE V. EF-NER, Primary Examiner.

W. I. GOODLIN, Assistant Examiner. 

1. A HYDRAULIC PISTON PUMP COMPRISING A ROTARY SHAFT HAVING AN ECCENTRIC PORTION, A PLURALITY OF RADIAL CYLINDERS DISPOSED AT SPACED ANGULAR INTERVALS ABOUT SAID ECCENTRIC PORTION OF SAID ROTARY SHAFT, AN INTERMEDIATE RING MEMBER SURROUNDING WITH A CERTAIN CLEARANCE SAID ECCENTRIC PORTION AND CONTROLLING THE RECIPROCATING MOVEMENTS OF THE PISTONS SLIDABLY MOUNTED IN SAID RADIAL CYLINDERS, SAID RING MEMBER HAVING FORMED ON EACH ONE OF ITS TWO END FACES FRUSTOCONICAL CAM SURFACES ADAPTED TO CO-ACT WITH FRUSTOCONICAL CAM SURFACES OF OPPOSITE INCLINATION FORMED RESPECTIVELY ON THE REGISTERING INNER FACES OF TWO ANNULAR MEMBERS SURROUNDING SAID ECCENTRIC AND CONCENTRIC THERETO, SAID ANNULAR MEMBERS BEING DISPOSED ON EITHER SIDE OF SAID RING MEMBER, AND RESILIENT MEANS CONSTANTLY URGING SAID ANNULAR MEMBERS TOWARDS EACH OTHER TO RETURN SAID RING MEMBER TO ITS MAXIMUM ECCENTRIC POSITION, SAID RING MEMBER BEING ADAPTED, BY PUSHING SAID ANNULAR MEMBERS OUTWARDS THROUGH THE MEDIUM OF THE PRESSURE EXERTED ON THE CO-ACTING INCLINED CAM SURFACES, TO RESUME MORE OR LESS REDUCED ECCENTRIC POSITIONS, DOWN TO ZERO THROW. 